Opponents contend legislators shouldn't force women to undergo any medical procedure and the bill will force at least two abortion clinics where providers lack admitting privileges to shut their doors.

The Republican-controlled Legislature passed the bill in mid-June. Walker, a Republican, could have chosen to sign it at any time since then but decided to do it on Friday in the middle of the long 4th of July holiday weekend. The measure's opponents accused him of trying to bury news of the signing.

"That's his prerogative. He's the governor," said Planned Parenthood of Wisconsin attorney Lester Pines. "But he's not going to win a profile in courage award."

Walker did not sign the bill in public, instead issuing a press release early in the afternoon including the bill in a list of 17 other measures he signed earlier the day.

"This bill improves a woman's ability to make an informed choice that will protect her physical and mental health now and in the future," the blurb noting the signing said.

Pines said Friday he plans to file a federal lawsuit with the American Civil Liberties Union arguing the law is unconstitutional. The lawsuit will include a request for a restraining order blocking the law from taking effect.

Under the bill, any woman seeking an abortion would have to get an ultrasound. The technician would have to point out the fetus' visible organs and external features to the woman. Abortion providers would have to have admitting privileges at a hospital within 30 miles to perform the procedures.

Republican supporters argue the ultrasound requirement is designed to help the woman bond with the fetus and convince her to save it. The admitting privileges mandate is meant to ensure an abortion provider can follow up with a patient at the hospital if an emergency arises, they say.

The bill is part of national GOP push to curtail abortions. North Dakota's governor, Republican Jack Dalrymple, signed a law this spring that outlaws abortions as early as six weeks into a pregnancy, making North Dakota the most restrictive state in the nation to get an abortion. The state's lone abortion clinic has filed a federal lawsuit seeking to block the law.

Republicans in Arkansas this spring passed a law that bans most abortions after 12 weeks. The American Civil Liberties Union of Arkansas and the Center for Reproductive Rights. A federal judge has temporarily blocked that law. A trial has been tentatively scheduled for next year.

Republicans in Alabama passed a law similar to the Wisconsin bill in April requiring abortion providers to have admitting privileges at a local hospital. The ACLU and Planned Parenthood filed a lawsuit contending the law would shut down three of the state's five clinics because doctors at the clinics haven't been able to get admitting privileges at nearby hospitals. A federal judge temporarily blocked the law in June.

The Wisconsin bill sparked a fierce debate in both the state Senate and Assembly as minority Democrats tried to push back. Republican leaders in the Senate abruptly halted a floor debate in that house. Senate President Mike Ellis, R-Neenah, flew into a rage as Democrats protested, pounding his gavel so hard he broke the base. Assembly Democrats, for their part, did a slow burn, complaining about the bill for hours. Republicans still rolled the bill through both houses.

"Wisconsin Republicans would be wise to spend less time intruding on Wisconsin women's very personal and private medical decisions and more time on the real issues facing our everyday families," Assembly Assistant Minority Leader Sandy Pasch said in a statement Friday.

Planned Parenthood and the ACLU's challenge in Wisconsin would closely resemble the one in Alabama, Pines said. It will argue the admitting privileges provision will force Planned Parenthood's Appleton clinic as well as Affiliated Medical Services in Milwaukee to close because physicians at both facilities lack admitting privileges to nearby hospitals. Women would still be able get abortions at Planned Parenthood facilities in Madison and Milwaukee, but Planned Parenthood argues many women would have to travel hundreds of miles to reach them.

"You cannot prohibit a doctor from performing a medical service merely because a private entity won't sanction that," Pines said. "It unconstitutionally infringes on the right of women in Wisconsin to have access to abortion services."